Lane change assistance is drive assistance to assist a driver in lane change of a vehicle. The lane change assistance is executed, for example, in a case where it is determined that the driver has an intention to change lane. In Japanese Translation of PCT International Application Publication No. 2006-515545, an apparatus is disclosed, which determines whether or not a driver has an intention to change lane based on a steering angle of a vehicle operated by the driver, a speed or an acceleration of the vehicle, or the like. In addition, in the publication, it is disclosed that the lane change assistance is performed by warning in a case where there is an obstacle in a blind spot of the driver at the time of changing lane based on the result of a determination of whether or not the driver has an intention to change lane.